package base64;



public final class  Base64 {

  static private final int  BASELENGTH         = 128;
  static private final int  LOOKUPLENGTH       = 64;
  static private final int  TWENTYFOURBITGROUP = 24;
  static private final int  EIGHTBIT           = 8;
  static private final int  SIXTEENBIT         = 16;
//  static private final int  SIXBIT             = 6;
  static private final int  FOURBYTE           = 4;
  static private final int  SIGN               = -128;
  static private final char PAD                = '=';
//  static private final boolean fDebug          = false;
  static final private byte [] base64Alphabet        = new byte[BASELENGTH];
  static final private char [] lookUpBase64Alphabet  = new char[LOOKUPLENGTH];

  static {

      for (int i = 0; i < BASELENGTH; ++i) {
          base64Alphabet[i] = -1;
      }
      for (int i = 'Z'; i >= 'A'; i--) {
          base64Alphabet[i] = (byte) (i-'A');
      }
      for (int i = 'z'; i>= 'a'; i--) {
          base64Alphabet[i] = (byte) ( i-'a' + 26);
      }

      for (int i = '9'; i >= '0'; i--) {
          base64Alphabet[i] = (byte) (i-'0' + 52);
      }

      base64Alphabet['+']  = 62;
      base64Alphabet['/']  = 63;

      for (int i = 0; i<=25; i++)
          lookUpBase64Alphabet[i] = (char)('A'+i);

      for (int i = 26,  j = 0; i<=51; i++, j++)
          lookUpBase64Alphabet[i] = (char)('a'+ j);

      for (int i = 52,  j = 0; i<=61; i++, j++)
          lookUpBase64Alphabet[i] = (char)('0' + j);
      lookUpBase64Alphabet[62] = (char)'+';
      lookUpBase64Alphabet[63] = (char)'/';

  }

  protected static boolean isWhiteSpace(char octect) {
      return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
  }

  protected static boolean isPad(char octect) {
      return (octect == PAD);
  }

  protected static boolean isData(char octect) {
      return (octect < BASELENGTH && base64Alphabet[octect] != -1);
  }

  protected static boolean isBase64(char octect) {
      return (isWhiteSpace(octect) || isPad(octect) || isData(octect));
  }

  /**
   * Encodes hex octects into Base64
   *
   * @param binaryData Array containing binaryData
   * @return Encoded Base64 array
   */
  public static String encode(byte[] binaryData) {

      if (binaryData == null)
          return null;

      int      lengthDataBits    = binaryData.length*EIGHTBIT;
      if (lengthDataBits == 0) {
          return "";
      }
            int      fewerThan24bits   = lengthDataBits%TWENTYFOURBITGROUP;
      int      numberTriplets    = lengthDataBits/TWENTYFOURBITGROUP;
      int      numberQuartet     = fewerThan24bits != 0 ? numberTriplets+1 : numberTriplets;
      char     encodedData[]     = null;

      encodedData = new char[numberQuartet*4];

      byte k=0, l=0, b1=0,b2=0,b3=0;

      int encodedIndex = 0;
      int dataIndex   = 0;
//      if (fDebug) {
//          System.out.println("number of triplets = " + numberTriplets );
//      }

      for (int i=0; i<numberTriplets; i++) {
          b1 = binaryData[dataIndex++];
          b2 = binaryData[dataIndex++];
          b3 = binaryData[dataIndex++];

//          if (fDebug) {
//              System.out.println( "b1= " + b1 +", b2= " + b2 + ", b3= " + b3 );
//          }

          l  = (byte)(b2 & 0x0f);
          k  = (byte)(b1 & 0x03);

          byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);

          byte val2 = ((b2 & SIGN)==0)?(byte)(b2>>4):(byte)((b2)>>4^0xf0);
          byte val3 = ((b3 & SIGN)==0)?(byte)(b3>>6):(byte)((b3)>>6^0xfc);

//          if (fDebug) {
//              System.out.println( "val2 = " + val2 );
//              System.out.println( "k4   = " + (k<<4));
//              System.out.println( "vak  = " + (val2 | (k<<4)));
//          }

          encodedData[encodedIndex++] = lookUpBase64Alphabet[ val1 ];
          encodedData[encodedIndex++] = lookUpBase64Alphabet[ val2 | ( k<<4 )];
          encodedData[encodedIndex++] = lookUpBase64Alphabet[ (l <<2 ) | val3 ];
          encodedData[encodedIndex++] = lookUpBase64Alphabet[ b3 & 0x3f ];
      }

      // form integral number of 6-bit groups
      if (fewerThan24bits == EIGHTBIT) {
          b1 = binaryData[dataIndex];
          k = (byte) ( b1 &0x03 );
//          if (fDebug) {
//              System.out.println("b1=" + b1);
//              System.out.println("b1<<2 = " + (b1>>2) );
//          }
          byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
          encodedData[encodedIndex++] = lookUpBase64Alphabet[ val1 ];
          encodedData[encodedIndex++] = lookUpBase64Alphabet[ k<<4 ];
          encodedData[encodedIndex++] = PAD;
          encodedData[encodedIndex++] = PAD;
      } else if (fewerThan24bits == SIXTEENBIT) {
          b1 = binaryData[dataIndex];
          b2 = binaryData[dataIndex +1 ];
          l = ( byte ) ( b2 &0x0f );
          k = ( byte ) ( b1 &0x03 );

          byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
          byte val2 = ((b2 & SIGN)==0)?(byte)(b2>>4):(byte)((b2)>>4^0xf0);

          encodedData[encodedIndex++] = lookUpBase64Alphabet[ val1 ];
          encodedData[encodedIndex++] = lookUpBase64Alphabet[ val2 | ( k<<4 )];
          encodedData[encodedIndex++] = lookUpBase64Alphabet[ l<<2 ];
          encodedData[encodedIndex++] = PAD;
      }

      return new String(encodedData);
  }

  /**
   * Decodes Base64 data into octects
   *
   * @param encoded string containing Base64 data
   * @return Array containind decoded data.
   */
  public static byte[] decode(String encoded) {

      if (encoded == null)
          return null;

      char[] base64Data = encoded.toCharArray();
      // remove white spaces
      int len = removeWhiteSpace(base64Data);
            if (len%FOURBYTE != 0) {
          return null;//should be divisible by four
      }

      int      numberQuadruple    = (len/FOURBYTE );

      if (numberQuadruple == 0)
          return new byte[0];

      byte     decodedData[]      = null;
      byte     b1=0,b2=0,b3=0,b4=0;
      char     d1=0,d2=0,d3=0,d4=0;

      int i = 0;
      int encodedIndex = 0;
      int dataIndex    = 0;
      decodedData      = new byte[ (numberQuadruple)*3];

      for (; i<numberQuadruple-1; i++) {

          if (!isData( (d1 = base64Data[dataIndex++]) )||
              !isData( (d2 = base64Data[dataIndex++]) )||
              !isData( (d3 = base64Data[dataIndex++]) )||
              !isData( (d4 = base64Data[dataIndex++]) ))
              return null;//if found "no data" just return null

          b1 = base64Alphabet[d1];
          b2 = base64Alphabet[d2];
          b3 = base64Alphabet[d3];
          b4 = base64Alphabet[d4];

          decodedData[encodedIndex++] = (byte)(  b1 <<2 | b2>>4 ) ;
          decodedData[encodedIndex++] = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
          decodedData[encodedIndex++] = (byte)( b3<<6 | b4 );
      }

      if (!isData( (d1 = base64Data[dataIndex++]) ) ||
          !isData( (d2 = base64Data[dataIndex++]) )) {
          return null;//if found "no data" just return null
      }

      b1 = base64Alphabet[d1];
      b2 = base64Alphabet[d2];

      d3 = base64Data[dataIndex++];
      d4 = base64Data[dataIndex++];
      if (!isData( (d3 ) ) ||
          !isData( (d4 ) )) {//Check if they are PAD characters
          if (isPad( d3 ) && isPad( d4)) {               //Two PAD e.g. 3c[Pad][Pad]
              if ((b2 & 0xf) != 0)//last 4 bits should be zero
                  return null;
              byte[] tmp = new byte[ i*3 + 1 ];
              System.arraycopy( decodedData, 0, tmp, 0, i*3 );
              tmp[encodedIndex]   = (byte)(  b1 <<2 | b2>>4 ) ;
              return tmp;
          } else if (!isPad( d3) && isPad(d4)) {               //One PAD  e.g. 3cQ[Pad]
              b3 = base64Alphabet[ d3 ];
              if ((b3 & 0x3 ) != 0)//last 2 bits should be zero
                  return null;
              byte[] tmp = new byte[ i*3 + 2 ];
              System.arraycopy( decodedData, 0, tmp, 0, i*3 );
              tmp[encodedIndex++] = (byte)(  b1 <<2 | b2>>4 );
              tmp[encodedIndex]   = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
              return tmp;
          } else {
              return null;//an error  like "3c[Pad]r", "3cdX", "3cXd", "3cXX" where X is non data
          }
      } else { //No PAD e.g 3cQl
          b3 = base64Alphabet[ d3 ];
          b4 = base64Alphabet[ d4 ];
          decodedData[encodedIndex++] = (byte)(  b1 <<2 | b2>>4 ) ;
          decodedData[encodedIndex++] = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
          decodedData[encodedIndex++] = (byte)( b3<<6 | b4 );

      }

      return decodedData;
  }

  /**
   * remove WhiteSpace from MIME containing encoded Base64 data.
   *
   * @param data  the byte array of base64 data (with WS)
   * @return      the new length
   */
  protected static int removeWhiteSpace(char[] data) {
      if (data == null)
          return 0;

      // count characters that's not whitespace
      int newSize = 0;
      int len = data.length;
      for (int i = 0; i < len; i++) {
          if (!isWhiteSpace(data[i]))
              data[newSize++] = data[i];
      }
      return newSize;
  }
}
